<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      const arr = [1, 2, 3, 4, 5, 6];
      const res = arr.reduce(function (r, v) {
        r = r + v; //3+3=6
        return r;
      }, 0);
      console.log(res);
      // let r = 0;
      // // 累加
      // arr.forEach((v) => {
      //   r = r + v;
      // });
      // console.log(r);
    </script>
  </body>
</html>
